Near-atomic in-situ architecture and membrane-coupled dynamics of the Vibrio cholerae sheathed flagellum

Abstract

The sheathed flagellum of Vibrio cholerae is a self-assembling membranous organelle that must coordinate axial assembly, sheath biogenesis, and rapid motor rotation. Here, we determine in-situ near-atomic structures of the sheathed flagellar motor inside intact cells. The motor anchors to the outer membrane through lipidated HL-rings without forming a membrane pore, thereby allowing axial assembly to drive sheath formation. Conserved LP-rings act as slide-rotary bushings that permit high-speed rotation within a dynamic envelope yet can constrict to seal the pore upon stress-induced ejection. We further show that stator activation requires a specific PomB-MotX interaction rather than peptidoglycan engagement. Together, these findings reveal how the distinctive architecture and dynamics of the sheathed flagellum promote V. cholerae motility, environmental survival, and persistent colonization of the human gut.